Sean Penn's infidelity to blame for divorce?

US actor Sean Penn's wife Robyn Wright Penn reportedly decided to serve him with divorce papers after she discovered that he had been cheating on her.

An American magazine has published a story which suggested that the couple's relationship ultimately disintegrated while they were on a weekend break and Wright Penn discovered her husband with other women.

The 41-year-old is said to have been staying in a separate hotel room to her spouse during their break in Lake Tahoe and when she visited him in his room she found him drinking with a pair of Russian women.

A source told Star magazine that she found out about her husband's wayward behaviour just before Christmas.

"During their last weekend together, Sean didn't spend much time with his wife - he booked her a separate suite. When Robin got fed up with being alone, she went over to his suite. She found him drunk with two Russian girls.

"He continued to party, while Robin was nowhere to be seen. When asked where his wife was, he answered, 'Who cares?'"

Penn and Wright Penn married in 1996 and have two children together.

Lonely and don't want to be?